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C28-8142_IBM_Standard_Tape_Label_1963


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                                                            File No. GENL 20
                                                            Form C28-8142




                   Systems Reference Library




IBM Standard Tape Label

This publication describes the format of the IBM
standard tape label and the conventions for its use.
The publication for any program that implements the
standard label will indicate that the program does so.

The standard label was designed for use on tapes for
the following tape units:

1.   IBM 729 II, III, IV, V, and VI Magnetic Tape Units

2. IBM 7330 Magnetic Tape Units

3. IBM 7340 Hypertape Drives

The IBM standard tape label contains 120 alphameric
positions and serves as both a header label and a trailer
label. There are two types of trailer labels:
end-of-file (EOF) trailer labels and end-of-reel (EOR)
trailer labels.




iJ   19F3. by Internati~nal Business Machines Corporation
Copies of this and other IBM publications can be obtained through IBM Branch
Offices. Address comments concerning the contents of this publication to
Programming Systems Publications, IBM Corporation, P. o. Box 390, Poughkeepsie, N. Y.
TAPE FORMATS AND LABELING                                    RECORDING METHOD

Figure 1 illustrates the use of the standard label in       All header and trailer labels must be written in
the basic tape data formats and on data tapes contain-      binary coded decimal (even parity) regardless of the
ing physical tape records (blocks) of checkpoint data.      recording method used for the data in the body of the
The various tape formats are described below.               file.

Single-Reel File
                                                            MODE (7340)LABELS
A single-reel file is a single file contained on a single
reel of tape. The first block is the standard label;        On 7340 tapes, both header and trailer labels must
this is followed by a tape mark. The data blocks come       be written in the unpacked mode, regardless of the
next; the last data block is followed by a tape mark.       mode in which the data records are written.
This tape mark is followed by an EOF trailer label
and then another tape mark.

Multi - File Reel                                           NOTES ON STANDARD LABEL FORMAT

                                                               1. Decimal notation is to be used in all label fields
A multi-file reel is a single reel of tape containing
                                                            containing numerical data.
two or more files. Each of these files is identical
                                                               2. Positions 6, 36, and 41 of the standard label are
to a single-reel file.
                                                            not to be used. The user is not to assume that these
                                                            positions will remain blank at all times.
Multi-Reel File

A multi-reel file is a single file contained on two or
                                                             STANDARD LABEL FORMAT
more reels of tape. Each reel of a multi-reel file
is identical in format to a single-reel file except that
all reels but the last one have EOR trailer labels.
                                                            Field 1: Label Identifier
The last reel of the file has an EOF trailer label
                                                            Positions: 1-5
instead of aILEOR trailer label.
                                                            The contents of this field identify the type of label as
Checkpoint Blocks on Data Tapes
                                                            follows:
                                                                Code          Meaning
The manner in which checkpoint blocks are recorded
                                                                1HDRb         Header label
on data tapes is specified in Field 19 of the standard
                                                               1EOFb          End-of-file trailer label
label.
                                                               1EORb          End-of-reel trailer label
                                                            Additional codes will be assigned by IBM as required.
HEADER LABE LS

When a tape is entered into a system of labeled tapes,
                                                            Field 2: Retention Period
the new tape should have a header label followed by
                                                            Positions: 7-10
a tape mark. The header label should contain
information in the Label Identifier and Reel Serial
Number fields only (see the format description              The contents of this field indicate the number of days
below).                                                     (0001-9998) the file is to be retained after the
                                                            creation date. The field should contain 9999 for files
TRAILER LABE LS                                             to which an expiration date is not applicable.

On 729 II, III, IV, V, and VI tapes and 7330 tapes,
only the Label Identifier and Block Count fields are        Field 3: Creation Date
written in the trailer label. 7340 tapes contain the        Positions: 11-15
above two fields in the trailer label and, in addition,
may contain any other trailer label fields because          The contents of this field indicate the year and day
of the ability of the 7340 to read backward.                of the year the file was created. The year (00-99)
    No trailer label field on any tape, other than the      occupies the first two positions of the field, and the
field entitled "For Optional Usage", is available to        day of the year (001-366) occupies the last three
the user for additonal label information; this is true      positions of the field (e. g. , January 31, 1962 would be
even if the fi~ld is not being used in the label.           be entered as 62031).

                                                                                                                  3
Field 4: File Identification                                 Field 10: Checksum Indicator
Positions: 16-25                                             Position: 46

The contents of this field are assigned by the user          The contents of this field indicate the presence of
and are unique to the file; this field identifies the        or absence of checksums.
entire file. Field 4 contains ten alphameric                    Code           Meaning
characters, including blanks.                                   -0--           Not applicable or no checksum
                                                                                present
Field 5: File Serial Number                                     1-9            Will be assigned by IBM for
Positions: 26-30                                                               various types of checksums

The contents of this field are identical to the contents
of Field 6 of the first or only reel of the file. This       Field 11: Block Sequence Indicator
field contains five alphameric characters, including         Position: 47
blanks.
                                                             The contents of this field indicate the presence or
Field 6: Reel Serial Number                                  absence of block sequencing.
Positions: 31-35                                                Code           Meaning
                                                                -0-            Not applicable or no block sequence
The contents of this field are assigned to the reel                            field used
when it enters the system. The field contains five              1-9            Will be assigned by IBM for various
alphameric characters, including blanks. The reel                              types of block sequence fields
serial number normally is also written on the
physical label of the reel for visual identification.
                                                             Field 12: Tape Checking/Interpreting Indicator
Field 7: Reel Sequence Number                                Position: 48
Positions: 37-40
                                                             The contents of this field indicate how bits are written
This is a four-digit field whose contents (0001-9999)        on the tape to provide a means of verifying and/or
indicate the order of the reel within a given file.          interpreting the data read from the tape.
                                                                Code      7030                       Others
Field 8: Reserve                                                -1-       Single odd parity without Binary
Positions: 42-44                                                          Error Correction Code
                                                                2         Single even parity without BCD
This field is reserved for future use to indicate the                     Error Correction Code
file number in a multifile reel. This file number               3         Single odd parity with     Not applicable
will be 1 in the label(s) associated with the first file                  Error Correction Code
on the reel, and will be increased by 1 for each
succeeding file on the reel.
                                                             Field 13: Tape Data Recording Technique Indicator
Field 9: Density Indicator                                   Position: 49
Position: 45
                                                             The contents of this field indicate the maximum number
The contents of this field give the density of the file as   of bits (not including check bits) that may be recorded
indicated by the programmed set density instruction.         as a unit (byte) on the tape.
(Density does not refer to packed and unpacked data. )          Code            Meaning
   Code           Meaning                                       -6--             729 or 7330
   -0--           Not applicable                                8               Hypertape
   1              Low density                                IBM will provide additional codes as they are required.
   2              High density




4
Field 14: Tape Data Processing Technique Indicator           Code            Meaning
Position: 50                                                 2               Checkpoint blocks are interspersed
                                                                             with data blocks.
The contents of this field indicate the number of bits       3               Checkpoint blocks are written as
(not including check bits) out of a byte that are to be                      consecutive blocks. No data blocks
treated as a unit in processing. The Hypertape codes                         are written.
are:                                                         4-9             Will be assigned by IBM if required
   Code            Meaning                                                   to indicate additional ways of
   4               Each unit of data consists of four                        recording checkpoint blocks.
                   bits (packed data).
   6               Each unit of data consists of six      Field 20: Block Count
                   bits (unpacked data).                  Positions: 67-72

Field 15: Creating System                                 This field is used in trailer labels only. Its contents
Positions: 51-54                                          indicate the number of physical tape records (blocks)
                                                          in the file that are used to record data. The block
The contents of this field denote the system that         count does not include header and trailer labels, tape
created the file, e. g., 7074.                            marks, segment marks, checkpoint records, or
Field 16: Record Format                                   other records not containing file data.
Position: 55                                              Field 21: Reserve
                                                          Positions: 73-74
The contents of this field indicate the record format
of the file.                                              This field is reserved for future use by IBM.
    Codes will be provided by IBM as they are required.
                                                          Field 22: For Disk Usage
Field 17: Record Length                                   Positions: 75-79
Positions: 56-60
                                                          This field is not to be used in tape labels.
For fixed-length records, the contents of this field
give the number of characters per logical data            Field 23: Reserve
record; for variable-length records, the contents of      Position: 80
this field give the number of characters in the largest
possible logical data record of the file.                 This field is reserved for future use by IBM.

Field 18: Blocking Factor/Size                            Field 24: For Disk Usage
Positions: 61-65                                          Positions: 81-85

For fixed-length records, the contents of this field      This field is not to be used in tape labels.
indicate the number of logical data records within
each tape block; for variable-length records, the         Field 25: Reserve
contents of this field indicate the number of             Positions: 86-91
characters in the largest possible tape block record
of the file.                                              This field is reserved for future use as a field
                                                          containing cycle information.
Field 19: Checkpoint Indicator
Position: 66                                              Field 26: Reserve
                                                          Positions: 92-100
The contents of this field indicate (1) the presence
and type or (2) the absence of checkpoint blocks.         This field is reserved for future use by IBM.
   Code            Meaning
  -0--             Not applicable or no checkpoint        Field 27: For Optional Usage
                   block                                  Positions: 101-120
   1               Checkpoint blocks immediately
                   follow the tape mark that comes        This field may, at the user's option, contain additional
                   after the header label. The check-     label data.
                   point blocks are followed by a tape
                   mark and then the next data block.

                                                                                                              5
C28-8142




ALPHABETIC LISTING OF LABEL FIELDS

The label positions occupied by each field are given
in parentheses following the field number.

                                         Field Number &                                                      Field Number &
Field Name                               Label Positions                     Field Name                      Label PositionS';

Block Count                              20 (67-72)                          Reel Serial Number             6 (31-35)
Block Sequence Indicator                 11 (47)                             Reserve                        8 (42-44)
Blocking Factor/Size                     18 (61-65)                          Reserve                        21 (73-74)
Checkpoint Indicator                     19 (66)                             Reserve                        23 (80)
Checksum Indicator                       10 (46)                             Reserve                       



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